9. Object Persistence

The standard method of saving and restoring object information in GNUstep
is through the use of the -encodeWithCoder: and -initWithCoder: methods.
Any object which requires persistence implements these methods. They are
used, for instance by Gorm, to save GUI interface elements. It is important
that all changes to these methods be backward compatible with previously
stored archives (for instance, those created by Gorm). The easiest way to do
this is to use class version numbers to indicate which archive configuration
should be read.
Modern implementations are expected to suppoort keyed archiving and should
use the same keys that are used in OSX.